1. Field of the Invention
The invention relates in general to a semiconductor light emitting structure, and more particularly to a semiconductor light emitting structure with current spreading grating.
2. Description of the Related Art
The light-emitting diode (LED) emits the light mainly by way of converting electrical energy into optical energy. The LED is mainly formed by semiconductors, wherein the semiconductor including higher ratio of holes carrying positive charges is referred as a P type semiconductor, and the semiconductor including higher ratio of electrons carrying negative charges is referred as a N type semiconductor. The joint between the P type semiconductor and the N type semiconductor forms a PN joint. When a voltage is applied to the positive electrode and the negative electrode of an LED, the electrons and the holes are combined together and emitted in the form of a light.
Due to the advantages such as long lifespan, low temperature and high energy utilization rate, LED has been widely used in backlight modules, lamps, traffic lights, and vehicle brake light in recent years, and gradually replaces conventional light sources.
Additionally, the luminance of an LED has much to do with the density of the current applied thereto. In general, the larger the current density, the higher the luminance. Therefore, how to make the current density uniformly distributed so as to increase the quantum efficiency inside the LED has become an imminent task for the industries.